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Discussion Starter · #1 ·
Hi,

I want to change the o2 sensors on my 03 Corolla.

What size oxygen sensor socket do I need, 3/8"?

Also have you changed the upstream o2 sensor before?

Was it easy?

Did you need to remove the heat shield on the manifold to get to it?

What are the torque specs on the o2 sensors?

Thanks for the help!!
 

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if your not getting any error codes and mileage isn't noticeably bad, I would leave well enough alone. we've gone to almost 150k on our 03 corolla without any code.

I am getting one now, not exactly sure why, but taking it out isn't that bad. Yes, you have to remove the heat shield, 4 bolts, 12mm 6pt socket or wrench. The sensor is 22mm. First i would start by putting some liquid wrench on them & letting sit for a wile. also, ryn car for a minute or two to warm up so thungs will loosen easier. unhook sensor wire. I have a craftsman 22mm box wrench, and the sensor clip fits through the round end, so i can use that to get a good hold on the sensor. Should turn off w/ some good pressure.

I don't know torque. Can't be that big of a deal, snug it back down reasonably tight, don't break it, don't leave it too loose.
 

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The front O2 sensor is easy to change exactly as Surfrider described. The heat shield was easy to get off on mine. Just take the heat shield bolts off, remove the O2 sensor cable from its plug, and work the heat shield over the sensor and the wire through the heat shield. However, if you get an aftermarket sensor, make sure the electrical cable is long enough before you put it in. I bought a Bosch sensor from Advanced Auto, got it screwed in, and found out the cable wouldn't reach the socket. The OEM sensor (Denso) is just barely long enough. If you get a generic sensor, you can use the old electrical plug and just attach the new sensor wires to the matching wires on the old cable. I would recommend soldering them if you go that way.
 

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Yes, I think you could get to it without taking off the heat shield. It just stinks bcz you won't be able to see the hex on the sensor, bcz the heat shield blocks the view, so you may not be able to see if you're stripping the metal.

Like I said, with a 22mm box wrench I was able to fit the enclosed, round end over the sensor's plug, all the way down the wire, and onto the sensor so I had a really good grip and great leverage (much better than w/ ratchet).

The heat shield is only 4 12mm bolts. if you lubricate them early and let sit, it shoudl come off really easily.
 

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I agree, it should be possible to take out w/o removing the heat shield with the O2 socket. You'll have to start the new one in by feel, just be careful not to cross thread it.
 
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